This invention relates to a brake shoe assembly and method of fabricating a brake shoe assembly for an automotive brake.
Typically, a brake shoe is fabricated to include an arcuate surface corresponding to the inner diameter of a brake drum. A brake lining is adhered to the arcuate surface of the brake shoe. Extending substantially perpendicular from the brake shoe on a side opposite the brake lining is a web structure. The web structure is typically attached to the arcuate surface by a fillet weld. Welding of any type introduces a great deal of heat into the parts being welded. This typically will distort the brake shoe and require additional manufacturing processes.
One process for correcting distortion is a coining process. In a coining process a welded brake shoe is placed within a die structure and forced back into the desired arcuate shape. The cost of the assembly of a typical brake shoe encourages the recycling of the brake shoes when the lining has worn and requires replacement. Typically, worn brake shoes are returned to the manufacturer for resurfacing and relining. The cost of such relining and reconditioning of the brake shoe can be prohibitive because of the additional equipment required.
Accordingly, it is desirable to construct a low cost brake shoe assembly that is both reconditionable and provides a construction that makes a disposal brake shoe economically feasible.
An embodiment of this invention includes first and second brake shoe sections, each including a lining surface and a mounting tab with a series of notches accommodating formation of an arcuate lining surface to match a specific brake drum diameter.
Each of the brake shoe sections defines a lining surface and a mounting tab. The mounting tab extends substantially perpendicular to the lining surface and provides a mating point with the mounting tab of the other section of the brake shoe assembly. Each mounting tab includes a series of notches along the length of the mounting tab. The notches in the mounting tab allow formation of the lining surface into an arcuate shape corresponding to the brake drum assembly. The mounting tabs are secured to each other at several mounting points. Each mounting point includes an opening for a rivet or other fastening device. Note that using a rivet introduces no heat during fabrication of the brake assembly. Because no heat is introduced during fabrication of the brake shoe assembly, subsequent forming processes to ensure the proper arcuate shape of the lining surface become unnecessary.
Alternatively, the mounting tabs are secured to one another using a spot welding process. The spot welding process exerts a specific amount of heat in precise and discreet locations on the mounting tab such that excessive heat is not introduced to the brake shoe assembly. Therefore, a brake shoe assembly formed with a spot welding process does not require subsequent manufacturing processes to assure the proper arcuate shape of the brake shoe assembly.
In another embodiment of the brake shoe assembly, a joint member is positioned between the first and second sections of the brake shoe assembly. The joint member is a u-shaped member that provides for mounting of the brake shoe in brake assemblies requiring a specific configuration. The joint member comprises a portion of the lining surface to which the brake lining is secured.
The brake lining of this invention can be bonded through the use of an adhesive as known by those skilled in the art. Alternatively, the brake lining may be riveted to the lining surface of the brake shoe assembly.
This invention includes a method for fabricating a brake shoe and includes the steps of forming first and second brake shoe sections from sheet metal to define a mounting tab and a lining surface. The method further includes removing material from the mounting tabs to form a series of notches to allow for the formation of an arcuate surface. The mounting tabs are then secured to one another to form the brake shoe assembly. A brake lining is then attached to the lining surfaces by any means as known to a worker skilled in the art.
The brake shoe assembly of this invention provides simple cost-efficient brake shoes to reduce manufacturing costs and make a disposable brake shoe economically feasible.